In an art of image recognition or biometric authentication, similarity between two images are often calculated. Generally, similarity between a recorded image recorded as a recorded template in advance and an input image input through a sensor or the like is calculated. A plurality of image data are often recorded in the recorded template in order to improve image matching accuracy. In this case, similarity between the input image and the plurality of the image data is calculated.
The biometric authentication includes one-to-one authentication and one-to-N authentication. The one-to-one authentication is an authentication in which a user is authenticated after the user is identified in advance with ID number or the like. The one-to-N authentication is an authentication in which matching of the plurality of recorded images of the recorded template is performed without identifying the user. With the one-to-N authentication, matching process of N number of recorded images is needed. In this case, time required for the authentication may get N times. There is a case where matching between one image and another image having different rotation angle is performed with respect to each user. In this case, the time required for the authentication may get longer. Japanese Patent Application Publication No. 2006-163726 (hereinafter referred to as Document 1) discloses an art in which the time required for the authentication is reduced with use of a plurality of image processing devices in parallel.
However, the art of Document 1 needs a plurality of image processing devices. In this case, cost may be increased.